Experimental Study on Strength Behaviour of Geogrid Reinforced Subgrade Soil

Abstract

This paper presents the summary of experimental program to evaluate the potential of KOBM (Klockner Oxygen Blown Maxhutte) slag to stabilize the geogrid-reinforced subgrade soil in Suva, Fiji. This KOBM slag is a by-product of steel manufacturing process in New Zealand. The standard California bearing ratio (CBR) laboratory tests were performed on the soil samples with various combinations of geogrid and KOBM slag, along with other geotechnical tests to determine the strength behaviour of subgrade soil. The laboratory experiments were undertaken to investigate the impact of using KOBM slag (0%, 5%, 10%, 15%, 20%) with single and double layers of geogrid reinforcement placed at H/2 and H/4 (where H is height of CBR mould) in the soil sample. The effect of geogrid reinforcement with respect to the position and number of layers with varying contents of KOBM on the strength behaviour of subgrade soil has been examined. Results of the current study indicate that there is a significant increase in CBR values for subgrade soil stabilized with KOBM and reinforced with geogrid. Maximum CBR value was observed in the soil sample reinforced with single geogrid layer placed at H/2 with 20% KOBM slag. This is the best outcome amongst all the combinations of KOBM, position/no. of layers of geogrid reinforcement in the current experimental study consisting of 50 experiments.